Process of and compound for treating rubber



Patented Sept. 20, 1932 7 were stares PATENT ormca enonen STAFFORD WHITBY, or MONTREAL, QUEBEC, CANADA, Assrenon, BY MEsNE' ASSIGNMENTS, TO THE ROESSLER, & HASSLAGHER GHEMIGAL COMPANY, A conno- RATION OF DELAWARE v V rnocnss on AND COMPOUND non TREATING RUBBER;

1T0 Drawing. I

the rate of vulcanization of rubber and sulphur mixtures, at the same time producing a vulcanized product having improved tenslle strength and other desirable mechanical properties. This object is attained through the use of my new compounds, and particularly by the use of the reaction product of liexamethylene tetramine benzyl chloride with a salt of mercapto benzo thiazole, as described more fully below.

The hexamethylene-tetramine benzyl ester of mercapto benzo thiazole has the advantage of being a solid crystalline substance which 7 can be readily and easily incorporated into a rubber mix. Furthermore, its melting point is sufiiciently high so that it remains a solid, evenin hot weather, and does not agglomerate or become sticky as do many other accelerators. Other properties of my accelerator which make it desirable are, that it can be used at both high and low-temperatures; its

acceleration of vulcanization is very'rapid, it

works well with carbon black stocks, so called non-blooming products can easily be made by S its use, and it can be made at low cost. V

The following example will serve to illustrate the process of making my improved accelerator;an aqueous solution of 9.5 grams of the sodium salt of mercaptobenzo thiazole was mixed with an aqueous solution of 13.3

Application filed August 2,1929. v Serial No. 383,176.

grams of the benzyl chloride addition p'rods not of hexamethylenetetramine. After stirring for some time, the turbid mixture became clear and 20 grams of a light yellow solid separated. This crude product was recrystallized from alcohol giving a pale yellow crystalline powder which melted at 140 C.

()ther salts of mercapto benzothiazole may be used, with the benzyl chloride addition product, but I prefer the use of theirelatively 1,,

inexpensive and easily prepared'sodium salt.

The product of this reaction has a definite melting point and I believe the reaction which takes place may be represented by the follow- I v 7 ing equation:

1 therefore reterto this new product as the hexamethylenetetramine benzyl ester of mercapto benzothi azole; that is, hexamethyL. enetetramine b enzyl mercapto benzothiazole.

The following examples illustrate the use of the product of the above reaction in the vulcanization of rubber:

. s am le 1 Ingredients I Parts Rubber; 100 Zinc oxide. V 111p ur; Hexamethylenetetramine benzyl mercaptobe izo th1azole t4 the mix was vulcanized at a temperature corresponding tosteam. at lbs. pressure, The

resulting vulcanized product when tested and hexamethylenetetramine with the sodium gave the following results:

This example illustrates the use of 'my accelerator in tiretread stock.v 7

ingredients Parts Smoked sheet rubber Oarbon Zinc oxide. S111phur 'Stcaric arid Hexamethylenetetramine' benzyl mercaptobenzo thiazole:

This mix was vulcanized lata temperature corresponding to 30' lbs. steam pressure. The

, resulting vulcanized product gave the following results wherrtested: r

400 per Stretch Cure. eentelon- Tensile I pver cent gafion I 7 Minutes I LbsJsqin. 630 1500 3160 v 620 1700 3434 I 40 610 1800 3488 My accelerator not only makes possible the production in a very short curing time and at a low temperature of vulcanized rubber of great toughness, tensile strength, and resalt of mercaptobenzo thiazole. V

3. As a new composition of matter, the hexamethylenetetraminebenzyl ester of mercapto benzo thiazole.

4. The process of preparing a rubber composition comprising vulcanizing rubber in the presence of the hexamethylenetetramine benzyl ester of mercaptobenzo thiazole.

5. Process for treating rubber or similar material which comprises combining with an unvulcanized rubber compounda vulcanizing agent and A;% to l%'by weight, calculated on the weight of the rubber in the compound, of the product obtained by reacting hexamethylenetetramine benzyl chloride with a metal salt of mercaptobenzothiazole.

" "6; A'r'ubb'er composition resulting from the vulcanization of a rubber mix comprising the product obtained when hexamethyl'enetetramine benzyl chloride is reacted with the sodi'um salt of mercaptobenz o thiazole.

Signed at London, England, this eighteenth day of July, A. D. 1929.

GEORGE STAFFORD WHITBY. l

sistance to abrasion when used" alone, .but

tends to produce results of the same superior nature when used with other accelerators and rubber compounding ingredients. It produces better results and is more economical to use than hexamethylenetetramine or mercaptobenzothiazole.

The amount of my new accelerator necessary to be incorporated into the rubber to obtain the above described superior results will generally amount to less than 1% and more than of the weight of the rubber used. Less or greater amountslof'accelerator than A to 1% will, of course, give similar results,

the exact amount for the best'resultsdepend ing upon the nature and amounts of the other ingredients of the mix to be vulcanized.

- Claims:

.1. The process for the preparation of the heXamethy-lenetetramine-benzyl ester of mercaptobenzo. thiazole which comprises react- ,ing the addition product of benzyl chloride and heixamethylenetetramine' with a metal 2. The process for the preparation of the:

hexanrethylenetetramine benzyl ester; ofmercaptobenz'othiazole which comprises react- 

